JPH05176206A - View finder - Google Patents

Abstract

PURPOSE:To provide a view finder with low power consumption. CONSTITUTION:A light emitted from a facial light emission source 14 is converted into point light sources by a light shield plate 12 in which very small holes are formed as a matrix. The light from the point light source is made incident on a lens array plate 13, in which the light is almost collimated and the resulting light is made incident f-a high polymer diffusion liquid crystal display device 11. The high polymer diffusion liquid crystal display device 11 modulates the on a light based on a video signal. A displayed picture is observed through magnification lenses 83a, 83b. It is not required to use a polarized plate by using the high polymer dispersion liquid crystal display device. Thus, the light utilizing efficiency is improved and the power consumption is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a viewfinder such as a liquid crystal display device for displaying an image taken by a video camera or the like.

[0002]

2. Description of the Related Art A liquid crystal display device is being used as a viewfinder of a video camera because it is lightweight, thin, and has low power consumption.

A conventional viewfinder will be described below. In addition, in this specification, a viewfinder includes at least a light source and a liquid crystal panel, which are integrally configured.

The external shape of the viewfinder (Fig. 7)
The cross-sectional structure is shown in FIG. 71 is a body, 7
2 is an eyepiece rubber, 81 is an eyepiece ring, and 82 is a TN liquid crystal display device. The body 71 has a TN liquid crystal display device 82,
A fluorescent tube box 87 as a surface emitting source is stored. Magnifying lenses 83a and 83b are arranged inside the body 71 and the eyepiece ring 81, and when the two lenses are combined, they function as a magnifying lens. By adjusting the insertion degree of the eyepiece ring 81, the focus can be adjusted according to the visual acuity of the user. The TN liquid crystal display device 82 has a liquid crystal layer having a thickness of several μm, has a mosaic color filter, and has a polarizing plate 85 that functions as a polarizer and an analyzer on both sides.
a and 85b are arranged. The viewfinder is attached to the main body of the video camera by the mounting bracket 73. Reference numeral 84 is an angle adjusting fitting for adjusting the angle of the polarizing plate 85a.

FIG. 9 shows a perspective view of the main elements shown in FIG. The surface emission source includes a fluorescent tube box 87 in which a fluorescent tube is arranged, and a diffusion plate 86 arranged in front of it.
It consists of and. The diffusion plate 86 is the fluorescent tube box 8
It is used to diffuse the light emitted from the light source 7 to form a surface light source with uniform brightness.

[0006]

The video camera is required to be compact and lightweight in terms of portability and operability. Therefore, introduction of a liquid crystal display device as a viewfinder display is expected. However, the power consumption of a viewfinder using a liquid crystal display device is considerably large. For example, the power consumption of a viewfinder using a TN liquid crystal display device is about 0.1 W for a TN liquid crystal display device and about 1.0 W for a light source as a backlight. The video camera has a limited battery capacity in order to ensure compactness and lightness, and when the viewfinder consumes a large amount of power, the continuous use time becomes short, which is a serious problem.

As described above, the liquid crystal display device using the TN liquid crystal requires polarizing plates on the incident side and the emitting side.
The total transmittance of the polarizing plates is about 30%. Therefore, high-luminance image display cannot be performed. In order to obtain a high-luminance image, it is necessary to increase the luminance of the surface emitting light source, which increases power consumption.

In view of the above problems, the present invention provides a viewfinder having a high light utilization rate.

[0009]

In order to solve the above-mentioned problems, a viewfinder according to the present invention comprises a surface emitting light source and a plurality of surface emitting light sources which are disposed on the entire surface of the surface emitting light source in order to convert the surface emitting light source into a point light source. A lens array plate as a light condensing means in which a plurality of microlenses for converting the light emitted from the point emission source into substantially parallel light are arranged in a matrix And a polymer-dispersed liquid crystal display device that modulates the light emitted from the light converging means.

[0010]

Since the liquid crystal display device using the polymer dispersed liquid crystal does not require a polarizing plate, the brightness of the light source for obtaining the necessary screen brightness is lower than that of the liquid crystal display device using the TN liquid crystal. can do. Therefore, the power consumption of the light source can be significantly reduced. There is no need for angle adjustment fittings such as polarizing plates.

[0011]

EXAMPLES The liquid crystal display device used in the present invention will be briefly described below. Polymer dispersed liquid crystals are roughly classified into two types depending on the dispersion state of liquid crystals and polymers. One is a type in which liquid crystals in the form of water droplets are dispersed in a polymer. The liquid crystal exists in the polymer in a discontinuous state. Hereinafter, such a liquid crystal is called PDLC, and
A liquid crystal panel using the liquid crystal is called a PD liquid crystal panel.
The other is a type that has a structure in which a polymer network is stretched around the liquid crystal layer. It looks like a sponge containing liquid crystal. The liquid crystal does not form a water drop and continuously exists. After that, such liquid crystal is
A liquid crystal panel using the above liquid crystal is called a C liquid crystal panel. In order to display an image with the above-mentioned two types of liquid crystal panels, light scattering and transmission are controlled.

The liquid crystal material is preferably a nematic liquid crystal, a smectic liquid crystal or a cholesteric liquid crystal, and may be a single liquid crystal compound or a mixture of two or more liquid crystal compounds or a mixture containing a substance other than the liquid crystal compound. Most preferred is a cyanobiphenyl nematic liquid crystal. The resin material is preferably a transparent polymer, and may be any of thermoplastic resin, thermosetting resin, and photocurable resin. Considering the ease of the manufacturing process, separation from the liquid crystal layer, and the like, it is preferable to use an ultraviolet curable resin. In particular, an ultraviolet curable acrylic resin is indicated, and a resin containing an acrylic monomer or an acrylic oligomer that is polymerized and cured by ultraviolet irradiation is particularly preferable. When these are irradiated with ultraviolet rays, only the resin undergoes a polymerization reaction to become a polymer, and the liquid crystal undergoes phase separation.

In order to obtain good contrast, it is necessary that the pore size of the water-drop-like particle system or polymer network is uniform to some extent, and that the size is in the range of 0.5 μm to several μm. Otherwise, the incident light scattering performance is poor and a good contrast cannot be secured. The average particle size of the water-drop-like liquid crystal or the average pore size of the polymer network is preferably in the range of 0.8 μm to 2.5 μm. Above all, the range of 1.0 μm to 2.0 μm is optimal. To satisfy such conditions, the resin must be a material that can be cured in a short time, such as an ultraviolet curable resin.

Although the present invention is not limited to one of PDLC and PNLC, PDLC will be described as an example for ease of explanation. Further, the PD liquid crystal display device and the PN liquid crystal display device are generically called a polymer dispersed liquid crystal display device.

The operation of the polymer dispersed liquid crystal display device will be briefly described with reference to FIGS. 10 (a) and 10 (b). (Fig. 1
0 (a) and (b) are explanatory views of the operation of the polymer-dispersed liquid crystal display device. In FIG. 10 (a) (b), 104
Is a liquid crystal in the form of water droplets, and 105 is a polymer. Pixel electrode 10
A TFT (not shown) or the like is connected to 2 and a voltage is applied to the pixel electrode by turning the TFT on and off to vary the liquid crystal alignment direction on the pixel electrode to modulate light. (Fig. 10
As shown in (a)), when no voltage is applied,
Each water droplet liquid crystal 104 is oriented in an irregular direction. In this state, the refractive index difference between the polymer and the liquid crystal is about 0.1, and the incident light is scattered. However, (Fig.
As shown in (b), when a voltage is applied to the pixel electrode, the liquid crystal is aligned. When the ordinary refractive index n _o of the liquid crystal 104 and the refractive index n _p of the volumer 105 completely match, the incident light is emitted from the array substrate 101 without being scattered.

FIG. 1 shows a sectional structure of a first embodiment of a viewfinder of the present invention. Reference numeral 12 is a light shielding plate. The light shielding plate 12 has holes of 0.2 mm or less arranged in a matrix. If the diameter of the hole is as small as possible, the contrast of the displayed image is improved, but the brightness is lowered.
Therefore, the hole diameter is determined in consideration of contrast and required brightness. The surface of the light shield plate 12 is formed in black, and absorbs unnecessary light generated between the lens array 13 and the light shield plate 12. In the lens array 13, microlenses are regularly formed in a matrix, and the centers of the holes formed in the light shielding plate 12 are located on the normal line passing through the center of one microlens. Also,
The light blocking plate 12 and the lens array 13 are arranged with a predetermined gap. The predetermined interval is approximately the focal length of the microlenses of the lens array plate 13. The microlenses of the lens array plate 13 have a flat surface, that is, a surface with a large radius of curvature, facing the light box 14 side. This makes it easy to satisfy the sine condition, and the brightness of the display screen of the liquid crystal display device 11 is uniform. This is to improve the property. The diameter of the microlenses of the lens array plate 13 is usually 2 mm or less. The smaller the diameter of the microlens array, the less visible the joints of the microlenses of the lens array plate 13 are in the display image. However, if it is too small, the lens array plate 1
3 becomes difficult, and the lens array plate 13
Is also limited by the thickness.

FIG. 2 is an enlarged view of the vicinity of the lens array plate 13. Further, (FIG. 3) is an explanatory diagram for explaining the operation of the viewfinder of the present invention. 31 is a microlens. The light emitted from the light box 14 is made into a point light source by the light blocking plate. The light is converted into light that is nearly parallel and has a narrow directivity by the condenser lens 31, and is incident on the liquid crystal display device 11 from the counter electrode (not shown) side. The liquid crystal display device 11 changes the amount of light transmission or the degree of scattering of light according to a video signal and displays an image. The observer brings his or her eyes into close contact with the eyepiece ring 81 to see the display image of the liquid crystal display device 11. That is, the position of the observer's pupil is almost fixed. The lens array plate 13 is the liquid crystal display device 1.
When all the pixels of 1 make light go straight, the light which comes out from the light shielding plate 12 and enters the effective area of the lens array plate 13 is made to enter the observer's pupil after passing through the magnifying lenses 83a and 83b. .. The combination of the two lenses 83a and 83b functions as a magnifying lens, so that an observer can magnify and see a small display image of the liquid crystal display device 11.

A mosaic color filter (not shown) is attached to the liquid crystal display device 11. Each color filter transmits any color of red, green, and blue. The film thickness of each color may be controlled by the composition of the filter. The film thickness of the filter is adjusted and formed when the filter is manufactured.
That is, the film thickness of the filter is changed between red, green and blue. The liquid crystal display device 11 has poor scattering characteristics for long-wavelength light (red). Therefore, if the liquid crystal layer thickness of the red pixel is made thicker than that of the other blue and green pixels, the scattering characteristic can be improved and the red, green, and blue gradation can be made uniform.

By adjusting the degree of insertion of the eyepiece ring 81 into the body 71, the focus can be adjusted according to the visual acuity of the user. The two positive lenses 83
It is also possible to configure a and 83b with one lens. This block diagram is shown in (FIG. 5). Alternatively, the two positive lenses 83a and 83b shown in (FIG. 1) can be removed and used in the configuration shown in (FIG. 4). In this case, the displayed image becomes small, but there is no problem in practical use.

FIG. 6 shows the construction of the second embodiment of the viewfinder of the present invention. The portion where the lens array plate 13 is arranged and the portion where the liquid crystal display device 11 is arranged are formed at an angle θ, and the body 71 has a dogleg shape. Light emitted from the lens array plate 13 obliquely enters the liquid crystal display device 11. The normal line passing through the center of the screen of the liquid crystal display device 11 and the magnifying lens 83a are matched. The angle θ depends on the scattering characteristics of the liquid crystal display device 11,
It is in the range of 3 to 20 degrees, preferably 4 to 15 degrees. Further, it is mechanically easy to make the angle θ variable.
When it is variable, the observer may adjust the angle θ at which the best contrast and the like can be seen while viewing the display image on the liquid crystal display device 11.

In the configuration shown in (FIG. 1), (FIG. 4) and (FIG. 5), the light traveling straight through the liquid crystal display device 11 is recognized as a display image, but in the configuration shown in (FIG. 6) the liquid crystal is displayed. The light scattered by the display device 11 and traveling obliquely is recognized as a display image. That is, the former is a positive display and the latter is a negative display. Liquid crystal display 1 for converting negative display to positive display
The polarity of the video signal added to 1 may be inverted and applied.

In the polymer dispersed liquid crystal display device 11,
The ratio of the transmitted light when the liquid crystal is on and the scattered light when the liquid crystal is off is called contrast. As shown in (FIG. 1), the lens array plate 1 is formed by allowing parallel light to enter the liquid crystal display device 11.
3. When the liquid crystal display device 11 and the eye position are matched, the transmitted light in the on state of the liquid crystal is larger than the scattered light in the off state. However, when light is obliquely incident on the liquid crystal display device 11 and the display image of the liquid crystal display device 11 is viewed as in the configuration shown in FIG. 6, the scattered light in the off state is larger than the transmitted light. There is an angle. Usually, the above phenomenon occurs when the angle θ is several degrees or more. In the configuration shown in (FIG. 6), the display image is darker than in the configuration shown in (FIG. 1), but the contrast becomes good if the angle θ is selected.

If the viewfinder of the present invention described above is used in a video camera, low power consumption, light weight and miniaturization can be easily realized.

The configuration of the switching element of the liquid crystal display device 11 of this embodiment is not limited to the TFT,
It is also effective in a liquid crystal display device using a two-terminal element such as a diode. Further, although the light is made to enter from the counter substrate side of the liquid crystal display device 11, it is not limited to this, and it is obvious that the same effect can be obtained by making it enter from the array substrate. As described above, the viewfinder of the present invention does not depend on the incident direction of light.

The surface emitting light source is not limited to the light box, and any surface emitting light source may be used.

Further, although the microlens plate in which the convex microlenses are arranged in a matrix is used as the condensing means, the microlens plate is not limited to this, and may be configured as shown in FIG. 11, for example. .. In FIG. 11, a plate having microlenses 111 having a refractive index of a predetermined portion is attached to the liquid crystal display device 11 with an adhesive layer 112. For the adhesive layer 112, an ultraviolet curable acrylic adhesive is used. The microlens 111 is a soda glass plate 13
It is formed by changing the refractive index by ion conversion that replaces sodium with other ions. The refractive index is 1.5 to 1.7, and the hexagonal honeycomb-like close-packed structure is obtained by photolithography.
This method can realize a size of one pixel and one microlens.

[0027]

As described above, in the viewfinder of the present invention, the light emitted from the light-shielding plate is converted into a light beam having a close directivity and a narrow directivity by the lens array plate and modulated by the polymer dispersed liquid crystal panel to form an image. Therefore, the polarizing plate can be eliminated. Therefore, it consumes less power and has less uneven brightness than a viewfinder using a TN liquid crystal display device. Further, if the viewfinder of the present invention is mounted on a video camera and used, the power consumption is low and the continuous use time can be significantly extended.

[Brief description of drawings]

FIG. 1 is a sectional view of a viewfinder according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the viewfinder of the present invention.

FIG. 3 is an operation explanatory diagram of the viewfinder of the present invention.

FIG. 4 is a sectional view of another embodiment of the viewfinder of the present invention.

FIG. 5 is a sectional view of another embodiment of the viewfinder of the present invention.

FIG. 6 is a cross-sectional view of another embodiment of the viewfinder of the present invention.

FIG. 7 is an external view of a viewfinder.

FIG. 8 is a sectional view of a conventional viewfinder.

FIG. 9 is an internal layout diagram of a conventional viewfinder.

FIG. 10 is an operation explanatory view of polymer dispersed liquid crystal.

FIG. 11 is a partially enlarged explanatory view of an embodiment of the viewfinder of the present invention.

[Explanation of symbols]

 11 polymer dispersed liquid crystal display device 12 light-shielding plate 13 lens array plate 14 light box 31 lens 71 body 72 eyepiece rubber 73 mounting metal fitting 81 eyepiece rings 83a, 83b magnifying lens 86 diffuser plate 101 array substrate 102 pixel electrode 103 counter electrode 104 water drop shape Liquid crystal 105 Polymer 106 Counter substrate 111 Microlens 112 Adhesive layer

Claims (7)

[Claims] 1. A surface emitting light source, a light shielding means for converting the surface emitting light source into a plurality of point light emitting sources, and a plurality of lenses for converting light emitted from the point light emitting source into substantially parallel light in a matrix form. A viewfinder comprising: a condensing unit arranged and a liquid crystal display device for modulating light emitted from the condensing unit. 2. A surface emitting light source, a light blocking means for converting the surface emitting light source into a plurality of point light emitting sources, and a plurality of lenses for converting light emitted from the point light emitting source into substantially parallel light in a matrix form. A viewfinder, comprising: a condensing unit arranged, a liquid crystal display device for modulating light emitted from the condensing unit, and an enlarging display unit for enlarging a display image of the liquid crystal display device. 3. A surface emitting light source, a light blocking means for converting the surface emitting light source into a plurality of point light emitting sources, and a plurality of lenses for converting light emitted from the point light emitting source into substantially parallel light in a matrix form. Light emitted from the light condensing means is provided with a condensing means arranged, a liquid crystal display device for modulating light emitted from the light condensing means, and a magnifying display means for enlarging a display image of the liquid crystal display device. A viewfinder characterized in that the liquid crystal display device is obliquely incident on the liquid crystal display device, and an optical axis of the magnifying display means and a normal line passing through a screen center of the liquid crystal display device are substantially coincident with each other. 4. The viewfinder according to claim 1, wherein the liquid crystal display device uses a polymer dispersed liquid crystal. 5. The light condensing means is characterized in that the light emitted from the point emission source is made incident on its effective area so that the light traveling straight through the liquid crystal display device reaches the observer's pupil. 1
The viewfinder according to claim 3. 6. The liquid crystal display device has an average particle diameter of liquid crystal droplets of liquid crystal or an average pore diameter of polymer network of 0.
The viewfinder according to claim 4, wherein the viewfinder has a thickness of 5 to 2.0 μm. 7. The liquid crystal display device has a liquid crystal layer thickness of 5 to 20.
The viewfinder according to claim 4, wherein the viewfinder is μm.